The present invention relates generally to a novel set of pliers and to a method for using said pliers to remove knockouts from steel outlet boxes, electrical conduit boxes or junction boxes and the like.
In the construction industry, it is widely known to use steel outlet boxes or junction boxes to serve as the point of origin, termination or coupling for electrical wiring, conduit and the like. The junction boxes are usually comprised of four side walls and a back wall. Since the direction of entry to the junction boxes varies, the side walls contain a plurality of removable knockouts. Further, to customize the placement of such metal boxes while also maintaining their integrity, the knockouts are only removed from the sides of the junction boxes which will receive wiring, conduit or the like. Normally the knockouts are coined or cut into the metal side walls of the respective junction box except for a tab, where the tab primarily secures the knockouts to the junction box.
The normal practice in the industry for removing knockouts is to place the head of a screwdriver within the circumference of a knockout and to strike the screwdriver with a blunt object, such as a hammer. This normally produces a force in one direction that fractures a portion of the knockout thereby causing the knockout to bend in relation to the supporting side wall of the junction box. The head of the screwdriver can then be used to further pry or bend the knockout in relation to the supporting side wall. With one side of the knockout now accessible, a pair of pliers or other gripping means can be used to secure the knockout and bend and twist the knockout until the remaining portion of the knockout is fractured thereby releasing the knockout. This process is time consuming and has a potential for damaging the junction box.
Also, it is sometimes the case that modification of junction boxes that are already installed will be performed. Under the normal practice in the industry, this may be problematic because fracturing the concentric knockout with a hammer and screwdriver requires adequate clearance and installed junction boxes may be located in tightly fitted areas.
The pliers that are currently available do not provide an adjustable plier jaw structure capable of quickly and easily removing knockouts. For example, as it is known in the art, pliers typically include two plier arms which are pivotally and adjustably interconnected, where the two plier arms further include opposing jaw portions that abut one another. As is further understood by those skilled in the art, the abutting portions of the pliers jaw allows the pliers to grip objects of varying sizes. This is typically performed by pivoting the plier arms in a manner to cause the two opposed jaw portions to form an open jaw, placing a particular object within the jaws, and then pivoting the plier arms in an opposite manner to cause the two opposed jaw portions to close on the object. The plier arms can also be adjusted to provide a larger or smaller jaw opening. An example of means for adjusting the size of the jaw opening are more clearly disclosed in U.S. Pat. No. 5,134,908. This patent discloses several different embodiments for pivotally and adjustably interconnecting two plier arms. Specifically, the jaws can be selectively adjusted to a variety of preset positions. Further examples of adjustable pliers may also be seen in U.S. Pat. No. 4,890,519, U.S. Pat. No. 4,901,609 and U.S. Pat. No. 5,676,029.
While the adjustable pliers shown in the prior art work well for their intended purpose and for removing knockouts once they have been fractured, they are not capable of quickly and easily fracturing the knockouts. In fact, this is why pliers are not currently used in the process of fracturing knockouts. This results from the fact that pliers are designed to provide force at a single point, and in primarily, equal and opposite directions. Thus, such pliers are not capable of providing the torque necessary to shear or fracture the knockout.
As a result of these noted deficiencies in the prior art, it is an object of the present invention to provide a set of pliers having an improved means for quickly and easily removing knockouts and improved means for providing opposing and offset forces which produce a greater quantity of sheer force upon a concentric or standard knockout.